What are the differences between implementing a @property with @dynamic or @synthesize? 8 s 8 @synthesize will generate getter and setter methods for your property. @dynamic just tells the compiler that the getter and setter methods are implemented not by the class itself but somewhere else (like the superclass or will be provided at runtime). … Read more
UIView and its subclasses all have the properties frame and bounds. What’s the difference? 1Best Answer 11 Short frame = a view’s location and size using the parent view’s coordinate system Important for: placing the view in the parent bounds = a view’s location and size using its own coordinate system Important for: placing the … Read more
Many classes in Cocoa/Cocoa Touch have the NS prefix. What does it mean? 9 s 9 It’s from the NeXTSTEP heritage.
I can’t find a clear answer on Apple documentation regarding Cocoa Autolayout about the difference between content hugging and compression resistance. Can somebody explain their usages and difference ? 8 s 8 A quick summary of the concepts: Hugging => content does not want to grow Compression Resistance => content does not want to shrink … Read more
It is to my understanding that one should use a forward-class declaration in the event ClassA needs to include a ClassB header, and ClassB needs to include a ClassA header to avoid any circular inclusions. I also understand that an #import is a simple ifndef so that an include only happens once. My inquiry is … Read more
I know how delegates work, and I know how I can use them. But how do I create them? 19 s 19 An Objective-C delegate is an object that has been assigned to the delegate property another object. To create one, you define a class that implements the delegate methods you’re interested in, and mark … Read more
I’m developing a Cocoa application, and I’m using constant NSStrings as ways to store key names for my preferences. I understand this is a good idea because it allows easy changing of keys if necessary. Plus, it’s the whole ‘separate your data from your logic’ notion. Anyway, is there a good way to make these … Read more
I’m trying to link a UILabel with an IBOutlet created in my class. My application is crashing with the following error. What does this mean? How can I fix it? *** Terminating app due to uncaught exception ‘NSUnknownKeyException’, reason: ‘[<UIViewController 0x6e36ae0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key XXX.’ 7 75
I would like to check to see if I have an Internet connection on iOS using the Cocoa Touch libraries or on macOS using the Cocoa libraries. I came up with a way to do this using an NSURL. The way I did it seems a bit unreliable (because even Google could one day be … Read more
